Common Vertical Axis Savonius-Darrieus Wind Turbines for Low Wind Speed Highway Applications

Abstract

Wind energy is considered to be the fastest growing alternative of fossil fuel and a clean energy source. In this research work a combination of common vertical axis wind turbine is designed and tested specifically for the sites having low wind speed availability. This combination of Savonius and Darrieus rotor blades on a common shaft provides the benefits of both the starting at very low wind speeds and good efficiency. This combination has been used to recapture the wind power available on the highways due to the movement of the vehicles. Savonius rotor blades being self-starting at low wind speeds help the Darrieus rotor blades to rotate which have greater efficiency than Savonius. Average wind speed available at the highway during this study is taken to be 4.8 m/s. Up to 37% efficiency is achieved by using this combination at a tip speed ratio of 0.9 and with no overlap conditions. With the increase in tip speed ratio, the overall efficiency and power coefficient increases. At high wind speeds, the tip speed ratio and power coefficient decreases.